In particular, I'm hoping they adapt Timothy Zahn's Thrawn trilogy--Heir to the Empire,Dark Force Rising,and The Last Command. The three books are especially beloved by the Star Wars fan community, which has oftentimes been greatly disappointed by the things Lucas has done to the SW universe.

Furthermore, the Thrawn trilogy has elements that would make it very attractive to the general audiences who loved the original films (and the prequels).

*We have Grand Admiral Thrawn as a powerful and threatening, but not wholly evil, villain. He's a man (sort of) who rose to a position of high honor and respect in Palpatine's Empire despite Palpatine's anti-alien racism and was entrusted with the Empire's continued military expansion in the outer regions of the galaxy while Palpatine and Vader ruled at home. He's someone who could provoke the same fascination/admiration that Vader did, and pose the same threat to our heroes.

*And we also have Joruus C'Boath, an insane Dark Jedi clone of a Jedi Master of the Old Republic, who can provide a Force-using villain and an opponent for Luke to have lightsaber duels with. He can also serve as a spiritual threat, much like how Vader and Palpatine were to Luke--his price for aiding Thrawn was that he would be given Luke Skywalker, the Princess Leia, and Han and Leia's two children to "mold."

*We have Mara Jade as a love interest for Luke, who never had one in the movies (except for Leia, who it turned out was his long-lost twin sister). Mara Jade was one of the Emperor's Hands, elite Dark Side-wielding assassins, and the last command she received from the dying Palpatine (this was via the Force) was to kill Luke Skywalker. This gnaws at her the entire trilogy, and leads to questions of loyalty. Character conflict is interesting too. :)

*It's set a decade after the original trilogy, much like how the prequels were set 20-30 years earlier. We'll get to see how Luke is reconstituting the Jedi Order and how Leia is putting together a New Republic. We can throw in other stuff, like how Han and Leia married and how the various warlords who emerged from the Empire's collapse were dealt with, as back-story.

Other than the fact there's a new trilogy coming, nothing has been announced. I'll keep everyone posted on what I hear.

It's a lovely trilogy. I agree with Matthew in recommending it. Zahn's a great writer: everything he does barrels along at an enjoyable speed. I am not so sure we're going to see Disney going with it, though. Lucas is staying on as a consultant, and has described his desire to oversee the handover of the franchise while he has time. Now, he won't have control, but he will have input on whatever Disney decides to do. He has shown absolutely no interest in the Expanded Universe. Funnily enough, some of the decisions he made in the Prequels lead to parts of the Thrawn Trilogy (and other EU works) being weird or "wrong". One thing that has excited me about this is that Joss Whedon directed that Avengers flick, a Marvel property, and Disney owns Marvel. Whedon has something of a Midas Touch, and anyone who's seen Firefly/Serenity knows that he is at home with the idea of a ragtag band of rebels facing off against an evil empire.

I think Lucas left it to other folk at Lucasfilm. It is a level of canon below the films.

Vader's given age is "wrong", leading to Zahn having to come up with the cunning suggestion that the Noghri answered in their solar year rather than galactic standard. Luke feels a strange sensation when the clones are about, and there's no mention of this in the prequels. There may be some other things, but those are what I remember offhand. It's been a couple of years since I myself reread the series.